1. Field of the Invention
The present invention relates to the field of off-highway truck bodies, and more particularly, to a tube-style truck body with a forward wedged front wall and side-sloped canopy.
2. Description of the Related Art
A traditionally built off-highway truck body is comprised of a plurality of bent steel ribs that form the skeletal structure or framework of the truck body, and solid steel plates overlying the ribs to form the truck box or container in which the material is held. The steel ribs are formed by bending flat sheets of steel and then welding them to the steel plates that form the truck box. These ribs are typically shaped like a “U” or a “V” with the open side of the “U” or “V” facing inward (attached to the steel plates).
The problem with bent steel ribs is that because they are open on one side, they do not tend to withstand the bending and twisting that accompanies the stress that is placed on the truck body during normal operations. One way to compensate for this stress is to increase the thickness of the steel used to form the bent ribs, which in turn increases the overall weight of the truck body. In addition, bent ribs are labor-intensive, which adds to the time required to manufacture the truck body. Because each rib is individually formed, there tends to be inconsistency in shape from one bent rib to another. It is also more difficult to achieve a solid weld with the bent ribs because of the inconsistency in the weld land.
Furthermore, due to current size restrictions in the press brakes that are used to form the bent ribs, long structural pieces such as the floor ribs cannot be made from one piece of bent steel but rather are formed by more than one bent rib welded end-to-end. The joining of the ribs end-to-end for the longer structural pieces further diminishes the structural integrity of the truck body and requires added manufacturing.
Another problem addressed by the present invention is the problem of material accumulation in the front corners of the truck body, where the front wall meets the floor and sidewalls. In traditional truck bodies, there is a ninety (90)-degree angle between the line formed by the joinder of the sidewall and the floor and the line formed by the joinder of the floor and front wall (this is illustrated in FIG. 11 below). This ninety (90)-degree angle can cause material, particularly highly cohesive material, to accumulate in the front corners of the truck body. This accumulation of material not only reduces the volume capacity of the truck body, but it also adds weight to the truck body when it is empty.
The present invention also addresses the problem of material retention on the canopy. With a traditional flat canopy, material tends to slough onto the canopy during loading. The retention of material on top of the canopy distorts the weight distribution of the vehicle by placing additional weight on the front axle. Flat canopies also cause side spill, as material falls from the canopy during travel. This occurrence leads to tire abuse and increased maintenance required on roads.
U.S. Pat. No. 6,520,590 (Feuereisen Azocar, 2003) attempts to alleviate some of the problems discussed above by providing a truck body with a front wall and floor that are elliptical in shape. This design reduces the number of beams (or bent ribs) that are required to support the truck box, thereby the overall weight of the truck body. Thus, the payload can be increased without exceeding the maximum gross weight allowed. According to the inventors, this design is less expensive to manufacture than the traditional truck body because fewer beams are required. The curved shape of the truck body avoids the concentration of strains that would otherwise damage the truck body, and it increases the discharge speeds of materials due to the non-existence of encounters with angles. Although attempting to address many of the same problems inherent in traditional truck bodies, the '590 patent does so in a manner very different than the present invention.
U.S. Pat. No. 6,565,1476 and (Fujan et at, 2003) U.S. Patent Application Pub. No. 2002/0180241 (Fujan) provide another off-highway truck body with a curved floor, curved front wall, curved sidewalls and curved cab protector (or canopy). According to the inventors, the steel ribs that are used to buttress the flat steel plates that form the truck body are costly and labor-intensive to fabricate and weld in place, the resulting connections are subject to fatigue, and the ribs increase the weight the truck body, thereby lowering the hauling capacity of the vehicle. Rather than developing a better rib, the inventors attempted to reduce or eliminate the need for ribs by providing a truck body that is entirely curved. Unlike the present invention, the canopy is curved upward, which would tend to retain material, rather than curved or angled downward, which would cause material to fall off of the canopy.
U.S. Patent Application Pub. No. 2004/0026959 (Kostecki) attempts to alleviate the problem associated with material build-up in the front corners of the truck body by providing removable wear plates that are installed between one or more of the front wall, side walls and floor.
U.S. Pat. No. 3,208,790 (Domes, 1965) attempts to solve the problems associated with using traditional U-shaped members (or bent ribs) to form the top rails of truck bodies. This invention provides a semi-circular top rail that curves down and over the outside of the sidewall and then is welded to the sidewall. One of the goals of this invention was to provide a curved surface that would resist any downward load applied to the top rail. Other goals were to decrease the number of parts required to build the top rail and to prevent the loader or shovel from inadvertently engaging the top rail during loading operations.
U.S. Pat. No. 6,481,785 (Coleman et al, 2002) describes a truck body design in which the junction between the floor and the upright panel (or front wall) is arcuate to facilitate the flow of materials being delivered into the dump body during the loading of the body (in other words, to direct the materials toward the floor).
U.S. Pat. No. 6,592,171 (Hinds, 2003) describes a way of bolstering the welded connection between the longitudinal and lateral ribs of a traditionally built truck body. In this invention, the ribs have a substantially U-shaped cross-section (as described above), which is particularly susceptible to the stresses associated with loading and unloading. Over time, these stresses can weaken the welds between the longitudinal and lateral ribs, causing those joints to crack. The invention covered by the '171 patent is a particular type of weld joint that is intended to strengthen the connection between the longitudinal and lateral ribs.